# [Tex/LaTex] TikZ Nodes not exactly centered

nodespositioningtikz-pgf

In my solution to draw a plot with point, it was pointed out that the nodes containing \textbullet and $\circ$ were not placed exactly centered at the specified point. I found this hard to believe but it does indeed appear to be the case.

Here is an image magnified to 2400% which shows this. The left pictures is:

\node [red] at (0,0) {\textbullet};
\draw [brown]  (0,0) circle (3pt);


and the right is:

\node [blue] at (1,0) {$\circ$};
\draw [brown]   (1,0) circle (3pt);


Clearly both are not centered at the given point.

## Questions:

1. I though that nodes were centered by default so what is different in this case?
2. How would you ensure that these are placed with their centers at the specified point?

## Code:

\documentclass{article}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}
\draw [very thin, gray] (-1,-1) grid (2,1);

\node [red] at (0,0) {\textbullet};
\draw [brown]  (0,0) circle (3pt);

\node [blue] at (1,0) {$\circ$};
\draw [brown]   (1,0) circle (3pt);
\end{tikzpicture}
\end{document}


The bounding box of a character always includes the baseline point:

\documentclass[tikz]{standalone}
\begin{document}
\begin{tikzpicture}
\foreach \txt[count=\c] in {\textbullet,$\circ$,',x}{
\node [inner sep=0pt,draw=red,line width=.1pt,text=violet](a) at (.25*\c,0) {\txt};
\draw [brown]  (.25*\c,0) circle (3pt);